The renewal project will continue the specific aims of: i) development of a physiologically equivalent normative model of the elbow joint for force analysis, ii) determination of the muscle and joint forces during various functions, iii) verification of the theoretical results, iv) examination of the relative contribution of individual joint support elements (articular surfaces, ligaments, and capsules) to joint stability, and v) decomposition of the resultant joint forces and moments into each support element. Data for establishing the normative model will be obtained by biplanar x-ray and direct force measurement methods. In resolving the indeterminate force analysis problem, the method of introducing additional constraint equations based on physiological and pathological considerations combined with the optimization method will be used. The theoretical results will be verified by both qualitative and quantitative electromyographic studies. The relative contribution of the joint support elements in resisting external load at the joint will be measured by performing load-displacement tests of the intact joint followed by sequential sectioning of individual elements. The joint contact area will be obtained by reversible cartilage staining technique and computerized tomography. The decomposition of the joint load will be achieved anlytically. The results of this study can be applied to numerous clinical problems, including the design of total elbow arthorplasty components and diagnosis and treatment of the ever-increasing athletic and traumatic afflictions of the elbow joint.